/*
 * Copyright (c) 2020 - present, Inspur Genersoft Co., Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.inspur.edp.web.formmetadata.filter;


import lombok.extern.slf4j.Slf4j;
import org.springframework.core.io.Resource;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.resource.*;

import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.ListIterator;

@Slf4j
public class UiLanguageResourceProvider extends ResourceHttpRequestHandler {
    private final ResourceHttpRequestHandler resourceHttpRequestHandler;
    public UiLanguageResourceProvider(ResourceHttpRequestHandler resourceHttpRequestHandler) {
        this.resourceHttpRequestHandler = resourceHttpRequestHandler;
    }

    public Resource getResource(String path, HttpServletRequest request) throws IOException {
        path = this.processPath(path);
        if (!StringUtils.hasText(path) || this.isInvalidPath(path) || this.isInvalidEncodedPath(path)) {
            return null;
        }

        ResourceResolverChain resolverChain = new UiLanguageResourceResolverChain(this.resourceHttpRequestHandler.getResourceResolvers());
        Resource resource = resolverChain.resolveResource(request, path, this.resourceHttpRequestHandler.getLocations());

        ResourceTransformerChain transformerChain = new UiLanguageResourceTransformerChain(resolverChain, this.resourceHttpRequestHandler.getResourceTransformers());
        if (resource != null) {
            resource = transformerChain.transform(request, resource);
        }

        return resource;
    }

    private boolean isInvalidEncodedPath(String path) {
        if (path.contains("%")) {
            try {
                String decodedPath = URLDecoder.decode(path, "UTF-8");
                if (this.isInvalidPath(decodedPath)) {
                    return true;
                }

                decodedPath = this.processPath(decodedPath);
                if (this.isInvalidPath(decodedPath)) {
                    return true;
                }
            } catch (IllegalArgumentException | UnsupportedEncodingException ignored) {
            }
        }

        return false;
    }
}



class UiLanguageResourceResolverChain implements ResourceResolverChain {
    @Nullable
    private final ResourceResolver resolver;
    @Nullable
    private final ResourceResolverChain nextChain;

    public UiLanguageResourceResolverChain(@Nullable List<? extends ResourceResolver> resolvers) {
        resolvers = resolvers != null ? resolvers : Collections.emptyList();
        UiLanguageResourceResolverChain chain = initChain(new ArrayList(resolvers));
        this.resolver = chain.resolver;
        this.nextChain = chain.nextChain;
    }

    private UiLanguageResourceResolverChain initChain(ArrayList<? extends ResourceResolver> resolvers) {
        UiLanguageResourceResolverChain chain = new UiLanguageResourceResolverChain(null, null);

        for(ListIterator<? extends ResourceResolver> it = resolvers.listIterator(resolvers.size()); it.hasPrevious(); chain = new UiLanguageResourceResolverChain(it.previous(), chain)) {
        }

        return chain;
    }

    private UiLanguageResourceResolverChain(@Nullable ResourceResolver resolver, @Nullable ResourceResolverChain chain) {
        this.resolver = resolver;
        this.nextChain = chain;
    }

    @Nullable
    public Resource resolveResource(@Nullable HttpServletRequest request, String requestPath, List<? extends Resource> locations) {
        return this.resolver != null && this.nextChain != null ? this.resolver.resolveResource(request, requestPath, locations, this.nextChain) : null;
    }

    @Nullable
    public String resolveUrlPath(String resourcePath, List<? extends Resource> locations) {
        return this.resolver != null && this.nextChain != null ? this.resolver.resolveUrlPath(resourcePath, locations, this.nextChain) : null;
    }
}

class UiLanguageResourceTransformerChain implements ResourceTransformerChain {
    private final ResourceResolverChain resolverChain;
    @Nullable
    private final ResourceTransformer transformer;
    @Nullable
    private final ResourceTransformerChain nextChain;

    public UiLanguageResourceTransformerChain(ResourceResolverChain resolverChain, @Nullable List<ResourceTransformer> transformers) {
        Assert.notNull(resolverChain, "ResourceResolverChain is required");
        this.resolverChain = resolverChain;
        transformers = transformers != null ? transformers : Collections.emptyList();
        UiLanguageResourceTransformerChain chain = this.initTransformerChain(resolverChain, new ArrayList(transformers));
        this.transformer = chain.transformer;
        this.nextChain = chain.nextChain;
    }

    private UiLanguageResourceTransformerChain initTransformerChain(ResourceResolverChain resolverChain, ArrayList<ResourceTransformer> transformers) {
        UiLanguageResourceTransformerChain chain = new UiLanguageResourceTransformerChain(resolverChain, null, null);

        for(ListIterator<? extends ResourceTransformer> it = transformers.listIterator(transformers.size()); it.hasPrevious(); chain = new UiLanguageResourceTransformerChain(resolverChain, it.previous(), chain)) {
        }

        return chain;
    }

    public UiLanguageResourceTransformerChain(ResourceResolverChain resolverChain, @Nullable ResourceTransformer transformer, @Nullable ResourceTransformerChain chain) {
        Assert.isTrue(transformer == null && chain == null || transformer != null && chain != null, "Both transformer and transformer chain must be null, or neither is");
        this.resolverChain = resolverChain;
        this.transformer = transformer;
        this.nextChain = chain;
    }

    public ResourceResolverChain getResolverChain() {
        return this.resolverChain;
    }

    public Resource transform(HttpServletRequest request, Resource resource) throws IOException {
        return this.transformer != null && this.nextChain != null ? this.transformer.transform(request, resource, this.nextChain) : resource;
    }
}
